Rep. Bob Inglis (R-S.C.), once a skeptic of global warming, got a hint that the political winds might be shifting when a longtime supporter warned that he might vote against Inglis if he “didn’t clean up his act on the environment.”

The warning came from Inglis’ eldest son, Robert Jr., now 22.

His daughter was no less blunt about the congressman’s refusal to embrace the view that global warming was being caused by human actions and that a serious response is needed. “I have three more kids coming up — and they seem to share the same view,” Inglis said.

Family pressure worked. Inglis traveled to Antarctica and, most recently, to Greenland to witness the effects of rising CO2 levels and temperatures. He now believes the science behind global warming. And he believes the politics are equally conclusive: Republicans will “get hammered” if they do not reckon with the issue soon.

You wouldn’t know it from listening to President Bush or most GOP congressional leaders, but a lot of smart Republican thinkers are coming to the same conclusion as Inglis.

The changing politics of global warming will be a useful gauge to measure change in Washington. Two questions loom.

The first is how Republicans will reposition themselves for a post-Bush era in which it appears that many ascendant issues — the environment and health care especially — are historically favorable terrain for Democrats.

The second is whether even powerful shifts in public opinion, as have clearly taken place on global warming, can force action in a Congress where partisan stalemate has been the operating mode on most difficult issues for over a decade.

Republican Sen. John Warner of Virginia has said his top goal for his remaining days in office is passing legislation to combat global warming.

Former House Speaker Newt Gingrich is warning that Republicans will get whacked in swing suburban areas if they keep acting like global warming does not exist.

And Ken Mehlman, the former top Bush strategist and one of the more innovative minds in GOP politics today, has been telling anyone who will listen that Republicans risk losing young voters if they do not seriously deal with the issue.

Now these Republicans will come armed with some pretty persuasive polling data. Environmental Defense, a special interest group pushing for limits on greenhouse gases and other global warming solutions, commissioned Republican pollster Whit Ayres to survey voters in the 49 most competitive House races.

The goal was to come up with polling data that even Republicans skeptics would consider trustworthy, especially when the data are attached to an environmental special interest group.

Eager to get the message out to Congress, Ayres provided Politico an exclusive look at their findings.

In a presentation similar to ones provided to congressional leaders on both sides of the aisle in recent days, Ayres illustrates how independents — who were responsible for ousting the GOP majority in 2006 — are unmistakably supportive of swift action to cut carbon emissions and require cuts in carbon dioxide emissions by cars, factories and power plants.

Ayres seemed most surprised that independents and, to a lesser extent, Republicans wanted the U.S. to act even if China and India, two big polluters with rapidly growing economies, did not.

The swing district independent voters said they were much more likely to support a candidate who votes to cut carbon emissions.

Republican voters were surprisingly supportive of efforts to combat global warming but also made it clear they were much less likely to hold members of Congress accountable if they failed to act anytime soon.

That helps explain why the leading presidential candidates seem in basic agreement that global warming exists but are very cautious in talking about the issue or solutions. Sen. John McCain (R-Ariz.), an early supporter of global warming legislation, is the big exception.

Republicans are split in three camps: a small but vocal group who think global warming is basically a hoax (26 percent of GOP voters in the Ayres poll said it does not exist); a big group that includes GOP presidential candidates Mitt Romney and Rudy Giuliani who agree the Earth is warming but are reluctant to embrace plans opposed by business or viewed as burdensome government regulation; and a growing number who are pushing for specific, market-based solutions now.

The latter group is on the rise. It includes corporations such as Duke Energy, lawmakers such as Warner and strategists such as Mehlman (who is also paid by a client to push for a market-based solution) who thinks it is in their best collective interest to move now on legislation.

The companies want to avoid tougher government regulations later, and the politicians want to avoid ceding the issue to Democrats and suffering a backlash from younger voters at the polls.

That said, it is unlikely Congress will make big changes in this election cycle.

Yes, the public agrees with Al Gore that rising temperatures are troublesome. Yes, both parties see this as an increasingly powerful political issue, especially among younger voters. Yes, the Democratic presidential candidates are putting forward ambitious plans to curb emissions.

But the base in both parties is skeptical of the most talked-about bill, one drafted by Warner and Sen. Joseph I. Lieberman, an independent from Connecticut, that would create a large-scale cap-and-trade system for emissions.

The legislation is designed to cap greenhouse emissions at 2005 levels by 2012. Some liberals and environmental groups say it does too little, too slowly. Some conservatives and corporate interests say it is too onerous or unnecessary.

Politics aside, it is not clear whether the public is ready to stomach the pocketbook costs of curtailing greenhouse gas emissions.

People want cleaner air, but are they willing to pay 30 percent more for natural gas to heat their home, or higher energy bills overall? Will they drive smaller cars or pay more to gas up their Durango? Probably not.

That is why even the most ambitious plans presented by the Democratic presidential candidates are setting goals so distant that they won’t be met until most of these contenders might be dead.

Inglis says he is studying the proper congressional response — three years after he was threatened with losing the family vote.